GB2388058A

GB2388058A - Method of feeding hydrogenous agent to a catalytic device using an internal combustion engine as the feed device

Info

Publication number: GB2388058A
Application number: GB0306197A
Authority: GB
Inventors: Ian Faye; Martin Maier
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2002-03-19
Filing date: 2003-03-18
Publication date: 2003-11-05
Anticipated expiration: 2023-03-18
Also published as: FR2837404A1; US20030177759A1; DE10212021A1; GB0306197D0; GB2388058B

Abstract

An apparatus 12 for exhaust gas treatment for an internal combustion engine 1 including a catalytic conversion unit 5 is characterised in that at least the internal combustion engine 1 is configured as a feed device for feeding hydrogenous heating agent, such as hydrogen, to the catalytic active conversion unit 5. The apparatus 12 substantially improves the cold start behaviour of the catalytic conversion unit 5, as well as considerably reduces the emission of pollutants by the internal combustion engine 1. A method for treating exhaust gases using apparatus 12 and a vehicle comprising apparatus 12 is also disclosed.

Description

"Apparatus for exhaust gas treatment for an internal combustion device"

The invention relates to an apparatus for exhaust gas treatment for an internal combustion device having a catalytically active conversion unit according to the preamble of Claim 1.

In keeping with the advancing state of knowledge statutory requirements controlling the emissions of motor vehicles for protection of health and the environment are becoming increasingly stringent. To meet these requirements harmful 15 exhaust gas components are removed from the exhaust gas by means, for example, of a catalytically active conversion unit, a so-called catalytic converter, in conjunction with the use of suitably modified fuels.

20 To perform their function, however, these catalytic converters necessitate certain operating temperature conditions which, especially during cold starting of an associated internal combustion device, e.g. a petrol or diesel engine, generally are not yet fulfilled.

In isolated cases the exhaust gas is already heated during the starting process of vehicles, for example, by means of heating coils arranged in the exhaust tract upstream of the catalytic converter, so that the catalytically active 30 coating of the catalytic converter is additionally and more rapidly heated.

In current vehicles measures internal to the engine are also being taken, such as changing of the ignition angle so

- ( that, in particular by means of retarded ignition, hotter exhaust gas is produced which then flows through the catalytic converter, thereby heating the latter more strongly. Also known is the feeding of the catalytic 5 converter with enriched exhaust gas by blowing in additional or secondary air, the thereby increased reaction rate of combustible gases with oxygen in turn additionally heating the exhaust gas and thus indirectly heating the catalytic converter.

In addition, suitable catalytic converters are known to be treatable especially rapidly through the supply of hydrogen.

These known devices for heating the exhaust gas or the 15 catalytic converter are, however, comparatively expensive, lead to increased, disadvantageous fuel consumption and/or offer detrimental thermal resistances.

In contrast to the above, it is the object of the invention 20 to propose an apparatus for exhaust gas treatment for an internal combustion device having a catalytically active conversion unit in which a heating device for heating the conversion unit by means of a hydrogenous heating agent is provided, which apparatus markedly reduces the system 25 related cost, significantly improves, in addition, the cold start behaviour of the catalytic converter and therefore considerably reduces, in particular, the emission of pollutants by the internal combustion device during the cold start phase.

( Setting out from an apparatus of the above-mentioned type, this object is achieved by the characterizing features of Claim 1.

5 Advantageous embodiments and refinements of the invention are made possible by the measures specified in the subsidiary claims.

Accordingly, the apparatus according to the invention is 10 distinguished by the fact that at least the internal combustion device is configured as a feed device for feeding the hydrogenous heating agent to the conversion unit. 15 With the aid of a corresponding configuration of the internal combustion device as a feed device according to the invention, the existing exhaust tract can advantageously be used as a conduit for feeding the hydrogenous heating agent or fuel. Consequently, a separate 20 feed line for feeding the hydrogenous heating agent to the conversion unit, as otherwise required by the state of the art, is omitted. A relatively long feed line is normally necessary because the conversion unit, particularly in vehicles, is generally located at a considerable distance 25 from the internal combustion device. For this reason, particularly the construction cost for the feeding of the hydrogenous heating agent to the conversion unit is reduced, so that an economically especially favourable embodiment can be realised according to the invention.

Unlike the case with the "normal" operation of the internal combustion device, ignition, in particular in the cylinder,

( is advantageously prevented, since otherwise the hydrogen contained in the heating agent would be chemically converted and therefore would no longer be available, or only in the form of heat' for heating the conversion unit.

According to the invention the internal combustion device can advantageously be configured as a "passive" feed device, the feed device substantially making possible a through-flow of the hydrogenous heating agent through the 10 internal combustion device to the conversion unit.

Possibly, existing inlet and exhaust valves or the like are opened almost simultaneously so that the preferably pressurized heating agent can flow through at least one cylinder or the like.

Equally, the internal combustion device can be advantageously configured as an "active" feed device, being provided, for example, as a pump or the like for actively pumping the hydrogenous heating agent through to the 20 conversion unit. For example, with this embodiment of the invention, especially if a reciprocating piston engine is used, the hydrogenous heating agent can be sucked in during an induction stroke and fed to the conversion unit or the catalytic converter during an exhaust stroke. In this case 25 the through-flow is advantageously promoted by means of suitable tuning of the closing and opening of the valves.

In this variant of the invention a separate pressure generating unit for feeding the heating agent to the conversion unit can possibly be dispensed with. This 30 advantageously reduces the cost of construction.

À In principle, an advantageous, electrical control unit can be provided for controlling, among other functions, suitable metering elements or valves, spark plugs, storage devices, compression ratios or the like. For example, at 5 least one operating parameter of the conversion unit and/or the internal combustion device, e.g. temperature or the like, is captured and made available to the control unit for controlling the whole internal combustion unit by means of advantageous sensors.

A feed element for feeding the heating agent is preferably arranged at least in the flow direction upstream of the internal combustion device. This makes it possible to feed the hydrogenous heating agent to the internal combustion 15 device in an especially simple manner.

The feed element preferably has at least two feed connections for feeding of the heating agent and of a fuel to the internal combustion device. Through the use of a 20 suitable feed element having at least two feed connections no additional elements are advantageously required, or existing valves or the like can optionally be used with only small modifications according to the invention.

25 In addition, the use of existing standard components such as "Bi-Fuel Injectors" is made possible by this variant.

Suitable "Bi-Fuel Injectors", in particular those of the Applicant, have been used hitherto, for example, for feeding fuel and a starting fuel for the internal 30 combustion device. For this purpose a starting fuel containing hydrocarbon and having a relatively low boiling

( point and/or an easily vaporised hydrogenous starting fuel is optionally used In this way, by means of suitable starting fuels, an 5 improvement of exhaust gas emissions, above all during the cold start phase of the internal combustion device, can be achieved. According to the invention the internal combustion device 10 is used as a feed device for feeding the hydrogenous heating agent to the conversion unit during a heating phase of the conversion unit, i.e. from a start until the attainment of a predefined operating temperature or until the end of a given duration. At that point a heating phase 15 of the internal combustion device can preferably be provided, in particular by means of the control unit. In this way ignition of the fuel, hydrogenous heating agent or heating agent-fuel mixture which has been supplied is advantageously made possible.

According to a particular variant of the invention a possibly pressurized storage reservoir for making available the hydrogenous heating agent is provided. This storage reservoir can optionally be configured to be refillable.

25 Alternatively or in combination therewith, at least one generating unit for generating the hydrogenous heating agent is provided in a preferred refinement of the invention. With the aid of this generating unit a corresponding storage reservoir can be dispensed with 30 entirely or dimensioned substantially smaller, without the supply of the hydrogenous heating agent when needed being thereby impaired. The generating unit preferably generates

! the hydrogenous heating agent in a particular operating phase. The generating unit advantageously takes the form of an 5 electrolysis unit. This makes it possible for the hydrogenous heating agent to be generated by electrolysis of water or the like by means of an electric current. Water as the starting material for electrolysis has particularly advantageous properties relevant to the environment and to 10 safety, as well as comparatively low cost. The electric current needed for electrolysis can be made available, for example, in a particular operating phase of the electrolysis unit in which, in particular, an electric generator of the internal combustion device and/or 15 optionally an electric energy accumulator can advantageously be used.

The electrolysis unit preferably takes the form of a membrane electrolysis unit, commercially available standard 20 components being usable and the hydrogenous heating agent being generated, for example, at a pressure of up to 30 bar. By this means the hydrogenous heating agent can optionally be fed to the internal combustion device or the conversion unit merely by opening and closing at least one 25 blocking or metering element such as a valve or the like.

Above all, alternatively to the use of the electrolysis unit, a reforming unit or the like can be provided to generate the hydrogenous heating agent for advantageously 30 converting at least partially the fuel or combustion agent of the internal combustion device. Known reformate purification stages, such as shift units or the like, can

( optionally be provided to increase the hydrogen content of the reformats. In this case an addition of hydrogenous reformats, and optionally reformate having carbon monoxide content, can usefully improve the behaviour of the internal 5 combustion device in certain operating states, e.g. during a cold start and/or full-load phase.

At least one storage element for storing the hydrogenous heating agent is advantageously provided. The storage 10 element is preferably configured in particular for temporary storage of the hydrogenous heating agent generated. For example, during operation of the internal combustion device and with the energy generated thereby, the hydrogenous heating agent can be generated without 15 dynamic time pressure and preferably stored temporarily by means of the storage element. Hydrogenous heating agent can optionally be produced at the so-called "best operating point" of the engine or of the generating unit with practically optimum efficiency, and possibly be stored 20 temporarily, e.g. during idling of the engine.

In an advantageous embodiment of the invention at least one pressure generating unit for pressurizing the hydrogenous heating agent is provided. For example' the hydrogenous 25 heating agent generated by the generating unit can be pressurised by means of a diaphragm pump or the like for temporary storage in the storage element.

For utilisation of the hydrogenous heating agent according 30 to the invention the pressurized heating agent can be fed without major usage of energy to the conversion unit and/or the internal combustion device to improve cold start

( g behaviour. The storage reservoir or storage element can optionally be filled with hydrogenous heating agent before the first start of the internal combustion device. The storage reservoir preferably at the same time takes the 5 form of a storage element.

An embodiment of the invention is illustrated in the drawing and is elucidated below with reference to the single Figure.

Fig. 1 shows in a block diagram an internal combustion engine 1 with a fuel tank 2, e.g. a petrol or diesel fuel tank, an alternator or generator 3, a battery 4 or accumulator and a catalytic converter 5.

The generator 3 is mechanically coupled by means of a connection 6 and during operation of the internal combustion engine 1 generates electrical energy which it supplies via a line 7 to a battery 4 and/or an electrolyser 20 8 and other electrical consumers 9, e.g. for air-

conditioning, infotainment, seat adjustment, electric window operation, etc. The electrolyser 8 can also be operated by means of 25 electrical energy from the battery 4. The electrolyser 8 converts water, in a manner not illustrated in detail, in particular into a hydrogenous fluid which is fed primarily by means of lines 13 and 14 to a storage reservoir 10 and/or directly (not shown) to the internal combustion 30 engine 1, and according to the invention is conducted further to the catalytic converter 5. The line 13 includes in general a pump for pressurizing the hydrogen.

According to the invention the internal combustion engine 1 is controlled by an electrical control unit (not shown in detail) in such a way that, for example, no fuel is burned 5 in the internal combustion engine 1 but the hydrogenous fluid is caused to flow through the same while undergoing as little chemical change as possible. This hydrogenous fluid is fed by means of an exhaust tract 11 already present in commercially available internal combustion 10 units 12 or vehicles to the catalytic converter 5, preferably during its cold start phase, so that its catalytically active coating is heated extremely rapidly to the necessary operating temperature. The cold start behaviour of the catalytic converter and of the entire 15 internal combustion unit 12 is thereby significantly improved, this being achieved, in addition, without major constructional cost.

For example, when starting the internal combustion unit 12 20 a starter or an "ignition key" is operated and in a first, relatively short phase the catalytic converter 5 is heated extremely rapidly to operating temperature according to the invention through the feeding of hydrogenous fluid preferably from the storage reservoir 10 through the 25 internal combustion engine 1. This phase, which is additional with respect to the state of the art, is imperceptible or hardly perceptible to the operator of the starter. 30 In a following, second stage fuel is preferably fed from the fuel tank 2 to the internal combustion engine 1, although it is possible alternatively to feed the

1 1 hydrogenous heating agent to the internal combustion engine 1. Optionally, the feeding of hydrogenous heating agent can take place simultaneously with the feeding of the fuel in a predefined proportion, whereby the exhaust gases 5 of the internal combustion engine 1 can be positively influenced. Commercially available standard components such as "Bi-Fuel Injectors" can, for example, be used for supplying the 10 hydrogenous fluid and/or the fuel, so that no additional valves are necessary for feeding the hydrogenous fluid to the internal combustion engine 1. Furthermore, the control of associated components and the implementation of the desired operating phases are thereby advantageously 15 controllable.

The emission of exhaust gases containing pollutants is fundamentally improved by the especially simple feeding of hydrogenous heating agent to the conversion unit or 20 catalytic converter 5 according to the invention, in particular during the cold start phase of the internal combustion unit 12. By this means values significantly below the relatively stringent current limit values for exhaust gases can be achieved.

l ( 1l List of reference numerals: 1 Internal combustion engine 5 2 Fuel tank 3 Generator 4 Battery 5 Catalytic converter 6 Connection 10 7 Line 8 Electrolyser 9 Consumer 10 Storage reservoir 11 Exhaust tract 15 12 Internal combustion unit 13 Line 14 Line

Claims

l f l3 Claims 1. An apparatus (12) for exhaust gas treatment for an

internal combustion device (1) including a 5 catalytically active conversion unit (5), a heating device (5) for heating the conversion unit (5) by means of a hydrogenous heating agent being provided, characterized in that at least the internal combustion device (1) is configured as a feed device (1) for 10 feeding the hydrogenous heating agent to the conversion unit (5).

2. Apparatus (12) according to Claim 1, characterized in that a feed element for feeding the heating agent is 15 arranged at least in the flow direction upstream of the internal combustion device (1).

3. Apparatus (12) according to any one of the preceding claims, characterized in that the feed element 20 includes at least two feed connections for feeding of the heating agent and of a fuel to the internal combustion device (1).

4. Apparatus (12) according to any one of the preceding 25 claims, characterized in that the feed element takes the form of an injector.

5. Apparatus (12) according to any one of the preceding claims, characterized in that at least one generating 30 unit (8) for generating the hydrogenous heating agent is provided.

/. 6. Apparatus (12) according to any one of the preceding claims, characterised in that the generating unit (8) takes the form of an electrolysis unit (8).

5 7. Apparatus (12) according to any one of the preceding claims, characterised in that the electrolysis unit (8) takes the form of a membrane electrolysis unit (8).

10 8. Apparatus (12) according to any one of the preceding claims, characterised in that the generating unit (8) includes at least one reforming unit for at least partially converting the fuel.

15 9. Apparatus (12) according to any one of the preceding claims, characterised in that at least one storage element (10) for storing the hydrogenous heating agent is provided.

20 10. Apparatus (12) according to any one of the preceding claims, characterised in that a pressure generating unit (8) for pressurising the hydrogenous heating agent is provided.

25 11. Apparatus (12) according to any one of the preceding claims, characterised in that the conversion unit takes the form of a heating device.

12. Apparatus (12) according to any one of the preceding 30 claims, characterised in that an electric control unit for controlling the feed element, the generating

f b unit (8) or pressure generating unit (8) and/or the storage element (10) is provided.

13. A vehicle having an apparatus (12) for exhaust gas 5 treatment for an internal combustion device (1), a heating device (S) for heating a catalytically active conversion unit (S) by means of a hydrogenous heating agent being provided, characterized in that the device (12) is configured according to any one of the 10 preceding claims.

14. A method for treating the exhaust gases of an internal combustion device (1) having a catalytically active conversion unit (5), a heating device (5) for heating 15 the conversion unit (5) by means of a hydrogenous heating agent being used, characterized in that the internal combustion device (1) is used as a feed device (1) for feeding the hydrogenous heating agent to the conversion unit (5) during a heating phase of 20 the conversion unit (5).

15. A method according to Claim 14, characterized in that an apparatus (12) according to any one of the preceding claims is used.

16. An apparatus substantially as described herein with reference to the accompanying drawing.

17. A vehicle substantially as described herein with 30 reference to the accompanying drawing.

18. A method substantially as described herein with reference to the accompanying drawing.